Loss Of Myelinated Fibers Research Articles

Neurologic Clinical, Electrophysiologic, and Pathologic Characteristics of Primary vs Secondary Neurolymphomatosis.

Neurolymphomatosis (NL) is characterized by lymphomatous infiltration of the peripheral nervous system presenting as the initial manifestation of a lymphoma (primary NL [PNL]) or in relapse of a known lymphoma (secondary NL [SNL]). This report details and compares the neurologic clinicopathologic characteristics of these 2 groups. This retrospective study was performed on patients diagnosed with pathologically confirmed NL in nerve between January 1, 1992, and June 31, 2020. Patient clinical characteristics, neurologic examination, imaging studies, EMG, and nerve biopsy data were collected, analyzed, and compared between PNL and SNL. A total of 58 patients were identified (34 PNL and 24 SNL). Time from neurologic symptom onset to diagnosis was longer in PNL at 18.5 months compared with 5.5 months in SNL (p = 0.01). Neurologic symptoms were similar in both patient groups and included primarily sensory loss (98%), severe pain (76%), and asymmetric weakness (76%). A wide spectrum of EMG-confirmed different neuropathy patterns were observed, but patients with SNL had increased numbers of mononeuropathies (n = 8) compared with PNL (n = 1, p = 0.01). MRI studies detected NL more frequently (86%) compared with fluorodeoxyglucose (FDG)-PET CT imaging studies (60%) (p = 0.007). Nerve biopsies revealed B-cell lymphoma (PNL n = 32, SNL n = 22), followed by T-cell lymphoma (PNL n = 2, SNL n = 2), with increased demyelination in both groups and increased axonal degeneration (p = 0.01) and multifocal myelinated fiber loss (p = 0.04) significant in SNL vs PNL. Identifying SNL resulted in patient treatment modifications but a worse prognosis compared with PNL (p = 0.025). While PNL and SNL are both primarily painful and asymmetric neuropathies with axonal and demyelinating features on EMG and nerve biopsy, SNL presents somewhat differently than PNL with fulminant, asymmetric often mononeuropathies better detected on MRI than FDG-PET/CT. The focal pattern of SNL is likely a result of residual cancer cells that evaded initial chemotherapy, which does not cross the blood-nerve barrier, and these cells can later recur and result in fulminant disease. Although still resulting in a poorer prognosis, identifying SNL is important because this changed treatment and management in every SNL case.

Clinical and biochemical characterization of asymptomatic carriers and symptomatic patients with hereditary transthyretin amyloidosis caused by TTR V30L mutation.

Hereditary transthyretin amyloidosis (ATTR) is an autosomal dominant disease characterized by amyloid fibril deposition. The TTR c.148G > T mutation (V30L) in ATTR is rarely reported, and its biochemical properties are unknown. Seven patients and two asymptomatic carriers from two unrelated families diagnosed with V30L variant of ATTR were included. Data on clinical manifestations, laboratory examination, electrophysiology, ophthalmological corneal confocal microscopy (CCM), pathology and molecular biological experiments was collected and analyzed. Most patients initially experienced paresthesia, with varying degrees of peripheral neuropathy, autonomic dysfunction, and cardiac involvement. Nerve conduction studies showed extensive motor and sensory nerve involvement in upper and lower limbs. CCM revealed reduced corneal nerve density and fiber length. Sural nerve biopsies indicated loss of myelinated nerve fibers, with neurogenic patterns in gastrocnemius muscle biopsies. Asymptomatic carriers had nearly normal electrophysiology but mild reductions in corneal nerve fiber density and length. Sural nerve biopsies in carriers showed mild reductions in small myelinated nerve fibers. V30L mutation impaired thermodynamic and kinetic stability of the mutant protein. Plasma TTR tetramer concentration was lower in ATTR V30L patients compared to healthy donors. Small molecule stabilizers failed to exhibit satisfactory inhibition on fibril formation of V30L mutation in vitro. This study highlights the multisystem involvement in ATTR V30L patients, including neuropathy and cardiac issues. Both patients and carriers showed abnormalities in nerve conduction, corneal microscopy, and pathology. The V30L mutation impaired protein stability and reduced plasma TTR tetramer levels. Small molecule stabilizers were ineffective, indicating a need for alternative treatments.

Episodic Neurological Dysfunction in X-Linked Charcot-Marie-Tooth Disease: Expansion of the Phenotypic and Genetic Spectrum.

X-linked Charcot-Marie-Tooth disease type 1 (CMTX1) is characterized by peripheral neuropathy with or without episodic neurological dysfunction. We performed clinical, neuropathological, and genetic investigations of a series of patients with mutations of the gap-junction beta-1 gene (GJB1) to extend the phenotypic and genetic description of CMTX1. Detailed clinical evaluations, sural nerve biopsy, and genetic analysis were applied to patients with CMTX1. We collected 27 patients with CMTX1 with GJB1 mutations from 14 unrelated families. The age at onset (AAO) was 20.9±12.2 years (mean±standard deviation; range, 2-45 years). Walking difficulties, weakness in the legs, and pes cavus were common initial symptoms. Compared with female patients, males tended to have a younger AAO (males vs. females=15.4±9.6 vs. 32.0±8.8 years, p=0.002), a longer disease course (16.8±16.1 vs. 5.5±3.8 years, p=0.034), and more-severe electrophysiological results. Besides peripheral neuropathy, six of the patients had special episodic central nervous system (CNS) evidence from symptoms, signs, and/or reversible white-matter lesions. Neuropathology revealed the loss of large myelinated fibers, increased number of regenerated axon clusters with abnormally thin myelin sheaths, and excessively folded myelin. Genetic analysis identified 14 GJB1 variants, 6 of which were novel. These findings expand the phenotypic and genetic spectrum of CMTX1. Although CMTX1 was found to have high phenotypic and CNS involvement variabilities, detailed neurological examinations and nerve conduction studies will provide critical clues for accurate diagnoses. Further exploration of the underlying mechanisms of connexin 32 involvement in neuropathy or CNS dysfunction is warranted to develop promising therapies.

Voluntary wheel running prevents formation of membrane attack complexes and myelin degradation after peripheral nerve injury

Regular aerobic activity is associated with a reduced risk of chronic pain in humans and rodents. Our previous studies in rodents have shown that prior voluntary wheel running can normalize redox signaling at the site of peripheral nerve injury, attenuating subsequent neuropathic pain. However, the full extent of neuroprotection offered by voluntary wheel running after peripheral nerve injury is unknown. Here, we show that six weeks of voluntary wheel running prior to chronic constriction injury (CCI) reduced the terminal complement membrane attack complex (MAC) at the sciatic nerve injury site. This was associated with increased expression of the MAC inhibitor CD59. The levels of upstream complement components (C3) and their inhibitors (CD55, CR1 and CFH) were altered by CCI, but not increased by voluntary wheel running. Since MAC can degrade myelin, which in turn contributes to neuropathic pain, we evaluated myelin integrity at the sciatic nerve injury site. We found that the loss of myelinated fibers and decreased myelin protein which occurs in sedentary rats following CCI was not observed in rats with prior running. Substitution of prior voluntary wheel running with exogenous CD59 also attenuated mechanical allodynia and reduced MAC deposition at the nerve injury site, pointing to CD59 as a critical effector of the neuroprotective and antinociceptive actions of prior voluntary wheel running. This study links attenuation of neuropathic pain by prior voluntary wheel running with inhibition of MAC and preservation of myelin integrity at the sciatic nerve injury site.

Granuloma, vasculitis, and demyelination in sarcoid neuropathy.

Despite the suggestion that direct compression by granuloma and ischemia resulting from vasculitis can cause nerve fiber damage, the mechanisms underlying sarcoid neuropathy have not yet been fully clarified. We examined the clinicopathological features of sarcoid neuropathy by focusing on electrophysiological and histopathological findings of sural nerve biopsy specimens. We included 18 patients with sarcoid neuropathy who had non-caseating epithelioid cell granuloma in their sural nerve biopsy specimens. Although electrophysiological findings suggestive of axonal neuropathy were observed, particularly in the lower limbs, all but three patients showed ≥1 abnormalities in nerve conduction velocity or distal motor latency. Additionally, a conduction block was observed in 11 of the 16 patients for whom waveforms were assessed; five of them fulfilled motor nerve conduction criteria strongly supportive of demyelination as defined in the European Academy of Neurology/Peripheral Nerve Society (EAN/PNS) guideline for chronic inflammatory demyelinating polyneuropathy (CIDP). In most patients, sural nerve biopsy specimens revealed a mild to moderate degree of myelinated fiber loss. Fibrinoid necrosis was observed in one patient, and electron microscopy analysis revealed demyelinated axons close to granulomas in six patients. Patients with sarcoid neuropathy may meet the EAN/PNS electrophysiological criteria for CIDP due to the frequent presence of conduction blocks. Based on our results, in addition to the ischemic damage resulting from granulomatous inflammation, demyelination may play an important role in the mechanism underlying sarcoid neuropathy.

A TRPV4 mutation caused Charcot-Marie-Tooth disease type 2C with scapuloperoneal muscular atrophy overlap syndrome and scapuloperoneal spinal muscular atrophy in one family: a case report and literature review

BackgroundCharcot-Marie-Tooth disease 2C (CMT2C) and scapuloperoneal spinal muscular atrophy (SPSMA) are different clinical phenotypes of TRPV4 mutation. The mutation of p.R316C has been reported to cause CMT2C and SPSMA separately.Case presentationHere, we reported a Chinese family harboring the same p.R316C variant, but with an overlap syndrome and different clinical manifestations. A 58-year-old man presented with severe scapula muscle atrophy, resulting in sloping shoulders. He also exhibited distinct muscle atrophy in his four limbs, particularly in the lower limbs. The sural nerve biopsy revealed severe loss of myelinated nerve fibers with scattered regenerating clusters and pseudo-onion bulbs. Nerve conduction study showed axon damage in both motor and sensory nerves. Sensory nerve action potentials could not be evoked in bilateral sural or superficial peroneal nerves. He was diagnosed with Charcot-Marie-Tooth disease type 2C and scapuloperoneal muscular atrophy overlap syndrome, whereas his 27-year-old son was born with clubfoot and clinodactyly. Electromyogram examination indicated chronic neurogenic changes and anterior horn cells involvement. Although there was no obvious weakness or sensory symptoms, early SPSMA could be considered for him.ConclusionsA literature review of the clinical characteristics in CMT2C and SPSMA patients with TRPV4 mutation suggested that our case was distinct due to the overlap syndrome and phenotype variation. Altogether, this case broadened the phenotype spectrum and provided the nerve biopsy pathological details of TRPV4-related neuropathies.

Pathogenic PSAT1 Variants and Autosomal Recessive Axonal Charcot-Marie-Tooth Disease With Ichthyosis

BackgroundBiallelic pathogenic phosphoserine aminotransferase 1 (PSAT1) variants generally cause a severe phenotype predominantly involving the central nervous system. Here, for the first time, we report two patients harboring pathogenic PSAT1 variants only manifested as polyneuropathy and ichthyosis. MethodsTwo patients from unrelated families presenting with polyneuropathy and ichthyosis were enrolled. Whole exome sequencing was performed to identify possible disease-causing variants. Their clinical, electrophysiological, imaging, biochemical, and pathologic changes were in detail assessed and investigated. ResultsHomozygous variant c.43G>C and compound heterozygous variants c.112A>C and c.43G>C in PSAT1 were identified in patients 1 and 2, respectively. Nerve conduction studies revealed preserved or mild slowing motor nerve conduction velocities of the median nerves in the two patients, whereas the compound motor action potential in patient 1 was severely decreased. Brain magnetic resonance imaging of the two patients found no abnormalities. Median nerve enlargement was observed on ultrasound in patient 1. Both patients had normal level of serine and glycine in plasma and cerebrospinal fluid. Sural nerve biopsy found severe loss of myelinated fibers. Electron microscopy revealed neurofilament accumulation and mitochondrial aggregation in axons. Both variants in PSAT1 were classified as likely pathogenic or pathogenic variants according to the standard guidelines. ConclusionsOur study confirms that pathogenic PSAT1 variants can cause a mild phenotype, predominantly as autosomal recessive axonal Charcot-Marie-Tooth disease.

Presumed vincristine ganglion cell toxicity resulting in binasal visual field loss

Vincristine sulfate, a common chemotherapeutic, can be neurotoxic, causing severe axonal damage and loss of myelinated fibers. We describe a patient with bilateral optic disc pallor and binasal visual field loss secondary to presumed Vincristine neurotoxicity.

Patterns of myelinated nerve fibers loss in transthyretin amyloid polyneuropathy and mimics.

ObjectiveThe present study was intended to analyze the characteristics of myelinated nerve fibers density (MFD) of transthyretin amyloid polyneuropathy (ATTR‐PN) and other similar neuropathies.MethodsA total of 41 patients with ATTR‐PN, 58 patients of other common peripheral neuropathies, and 17 age‐and gender‐matched controls who visited the First Hospital of Peking University and performed sural nerve biopsy between June 2007 and August 2021 were included for analysis of MFD.ResultsExcept the vasculitic neuropathy group, the total and small MFD of patients in the ATTR‐PN group were significantly lower than those of other disease groups. There was an obvious negative correlation between the total MFD and the disease course in the ATTR‐PN group. The disease course of early‐onset and late‐onset symptoms was similar, but the loss of large myelinated nerve fibers (MF) was more severe for the latter. In addition, all late‐onset and most early‐onset patients had severely reduced MFD after a 2 years' disease course. The MFD in ATTR‐PN patients was negatively correlated with Neuropathy Impairment Score (NIS) and Norfolk Quality of life‐diabetic neuropathy (Norfolk QOL‐DN) score.ConclusionMF is lost differently in ATTR‐PN and in other common peripheral neuropathies. The late‐onset and early‐onset ATTR‐PN patients have different patterns of loss of large and small MF.

091 CIDP mimic in a patient with HIV; An unusual presentation of POEMS syndrome

A 37-year old woman with HIV on antiretrovirals (undetectable viral load; CD4 count 520) presented with a painful length dependant sensorimotor polyneuropathy. Investigations showed mild neutropenia, IgA 5.2g/L without paraprotein. Nerve conduction studies indicated a demyelinating polyneuropathy. CSF was acellular with protein 1193mg/L. Despite multiple courses of IVIg and subsequently pulsed IV and oral steroids, her power deteriorated considerably. A nerve biopsy showed loss of myelinated fibres with inflammation. On reinvestigation an IgA lambda paraprotein (5.2g/L) with raised VEGF (1190ng/L) was identified. Bone marrow demonstrated 8% plasma cells; a CT-PET was normal. A diagnosis of POEMS syndrome was made and chemotherapy commenced. A full VEGF response and resolution of neuropathic pain was seen 6-months post treatment initiation; however, treatment was complicated by venous sinus thrombosis and hypocortisolaemia.POEMS syndrome is a rare plasma cell dyscrasia with protean clinical manifestations, though all develop a progressive peripheral neuropathy. There is no reported association with HIV and POEMS, though HIV in association with CIDP has been reported and is usually responsive to treatment. It is important to challenge a CIDP diagnosis when refractory to treatment with atypical features, particularly severe neuropathic pain, and to repeat investigations if clinical suspicion is high.liamcarroll@nhs.net

Diagnostic Challenges in Late Onset Multiple Acyl-CoA Dehydrogenase Deficiency: Clinical, Morphological, and Genetic Aspects.

BackgroundMultiple acyl-CoA dehydrogenase deficiency (MADD) is an autosomal recessive disorder of fatty acid oxidation due to deficiency of the mitochondrial electron transfer chain. The late-onset form is characterized by exercise intolerance, muscle weakness, and lipid storage in myofibers. Most MADD patients greatly benefit from riboflavin supplementation.Patients and methodsA retrospective study was conducted on patients with a diagnosis of vacuolar myopathy with lipid storage followed in our neuromuscular unit in the last 20 years. We selected 10 unrelated patients with the diagnosis of MADD according to clinical, morphological, and biochemical aspects. Clinical features, blood tests including serum acylcarnitines, EMG, and ENG were revised. Muscle biopsy was performed in all, and one individual underwent also a sural nerve biopsy. Gene sequencing of ETFA, ETFB, and ETFDH was performed as a first-tier genetic analysis followed by next-generation sequencing of an hyperCKemia gene panel in patients with undefined genotypes.ResultsClinical evaluation at onset in all our patients showed fatigue and muscle weakness; four patients showed difficulties in chewing, three patients complained of dysphagia, two patients had a dropped head, and a patient had an unexpected ataxia with numbness and dysesthesia. Laboratory blood tests revealed a variable increase in serum CK (266–6,500) and LDH levels (500–2,000). Plasma acylcarnitine profile evidenced increased levels of different chains intermediates. EMG was either normal or showed myogenic or neurogenic patterns. NCS demonstrated sensory neuropathy in two patients. Muscle biopsies showed a vacuolar myopathy with a variable increase in lipid content. Nerve biopsy evidenced an axonal degeneration with the loss of myelinated fibers. ETFDH genetic analysis identifies 14 pathogenic variants. Patients were treated with high doses of riboflavin (400 mg/die). All of them showed a rapid muscle strength improvement and normalization of abnormal values in laboratory tests. Neuropathic symptoms did not improve.ConclusionOur data confirmed that clinical features in MADD patients are extremely variable in terms of disease onset and symptoms making diagnosis difficult. Laboratory investigations, such as serum acylcarnitine profile and muscle biopsy evaluation, may strongly address to a correct diagnosis. The favorable response to riboflavin supplementation strengthens the importance of an early diagnosis of these disorders among the spectrum of metabolic myopathies.

Characterisation of the pathophysiology of neuropathy and sensory dysfunction in a mouse model of recessive dystrophic epidermolysis bullosa.

Recessive dystrophic epidermolysis bullosa (RDEB) is a rare genetic condition in which mutations in the type VII collagen gene ( COL7A1 ) lead to decreased expression of this anchoring protein of the skin, causing the loss of stability at the dermo-epidermal junction. Most patients with RDEB experience neuropathic pain and itch due to the development of a small fibre neuropathy, characterised by decreased intraepidermal innervation and thermal hypoaesthesia. To understand the physiopathology of this neuropathy, we used a mouse model of RDEB (Col7a1 flNeo/flNeo ) and performed a detailed characterisation of the somatosensory system. Col7a1 flNeo/flNeo mice showed a decrease in heat sensitivity, an increase in spontaneous scratching, and a significant decrease in intraepidermal nerve fibre density in the hindpaw; these changes were distal because there was no significant loss of unmyelinated or myelinated fibres in the nerve trunk. Of interest, we observed a decrease in axon diameter in both myelinated and unmyelinated fibres. This axonal damage was not associated with inflammation of the dorsal root ganglion or central projection targets at the time of assessment. These results suggest that in RDEB, there is a distal degeneration of axons produced by exclusive damage of small fibres in the epidermis, and in contrast with traumatic and acute neuropathies, it does not induce sustained neuroinflammation. Thus, this animal model emphasizes the importance of a healthy cutaneous environment for maintenance of epidermal innervation and faithfully replicates the pathology in humans, offering the opportunity to use this model in the development of treatments for pain for patients with RDEB.

Loss and dispersion of superficial white matter in Alzheimer's disease: a diffusion MRI study.

Pathological cerebral white matter changes in Alzheimer’s disease have been shown using diffusion tensor imaging. Superficial white matter changes are relatively understudied despite their importance in cortico-cortical connections. Measuring superficial white matter degeneration using diffusion tensor imaging is challenging due to its complex organizational structure and proximity to the cortex. To overcome this, we investigated diffusion MRI changes in young-onset Alzheimer’s disease using standard diffusion tensor imaging and Neurite Orientation Dispersion and Density Imaging to distinguish between disease-related changes that are degenerative (e.g. loss of myelinated fibres) and organizational (e.g. increased fibre dispersion). Twenty-nine young-onset Alzheimer’s disease patients and 22 healthy controls had both single-shell and multi-shell diffusion MRI. We calculated fractional anisotropy, mean diffusivity, neurite density index, orientation dispersion index and tissue fraction (1-free water fraction). Diffusion metrics were sampled in 15 a priori regions of interest at four points along the cortical profile: cortical grey matter, grey/white boundary, superficial white matter (1 mm below grey/white boundary) and superficial/deeper white matter (2 mm below grey/white boundary). To estimate cross-sectional group differences, we used average marginal effects from linear mixed effect models of participants’ diffusion metrics along the cortical profile. The superficial white matter of young-onset Alzheimer’s disease individuals had lower neurite density index compared to controls in five regions (superior and inferior parietal, precuneus, entorhinal and parahippocampus) (all P < 0.05), and higher orientation dispersion index in three regions (fusiform, entorhinal and parahippocampus) (all P < 0.05). Young-onset Alzheimer’s disease individuals had lower fractional anisotropy in the entorhinal and parahippocampus regions (both P < 0.05) and higher fractional anisotropy within the postcentral region (P < 0.05). Mean diffusivity was higher in the young-onset Alzheimer’s disease group in the parahippocampal region (P < 0.05) and lower in the postcentral, precentral and superior temporal regions (all P < 0.05). In the overlying grey matter, disease-related changes were largely consistent with superficial white matter findings when using neurite density index and fractional anisotropy, but appeared at odds with orientation dispersion and mean diffusivity. Tissue fraction was significantly lower across all grey matter regions in young-onset Alzheimer’s disease individuals (all P < 0.001) but group differences reduced in magnitude and coverage when moving towards the superficial white matter. These results show that microstructural changes occur within superficial white matter and along the cortical profile in individuals with young-onset Alzheimer’s disease. Lower neurite density and higher orientation dispersion suggests underlying fibres undergo neurodegeneration and organizational changes, two effects previously indiscernible using standard diffusion tensor metrics in superficial white matter.

Light-Chain Amyloidosis With Peripheral Neuropathy as an Initial Presentation.

Objective: This study aimed to better understand the clinical, electrophysiological, pathological features and prognosis of peripheral nerve involvements in primary immunoglobulin light-chain (AL) amyloidosis.Methods: We retrospectively reviewed the clinical data of eight AL amyloidosis patients with peripheral neuropathy as the initial presentation including clinical features, histopathological findings and treatment.Results: There were seven males and one female aged from 52 to 66 years. Initial symptoms included symmetrical lower extremity numbness, lower extremity pain and carpal tunnel syndrome. Seven patients suffered from severe pain and required pain management. Six patients had predominant autonomic dysfunction. Six patients had cardiac involvement, and one patient had renal involvement. Monoclonal proteins were found in all patients, with IgA λ in one, IgG λ in two, λ alone in three, κ alone in one and IgM κ in one. Sural nerve biopsies were performed in 7 cases, all of which showed amyloid deposition in the endoneurium (in the perivascular region in some cases), in addition to moderate to severe myelinated fiber loss with axonal degeneration. Six patients were treated with combined chemotherapy. In three patients who began chemotherapy earlier (6–10 months after onset), two achieved a hematological complete response, and one achieved a partial response. three patients who had delayed chemotherapy (36 months after onset) died between 5 and 12 months after diagnosis.Conclusion: Early recognition of AL amyloidosis with peripheral neuropathy as the initial symptom is very important. Nerve biopsy can help to make the diagnosis. Early diagnosis and chemotherapy are critical to achieve better outcomes.

The Pathological Features of Common Hereditary Mitochondrial Dynamics Neuropathy.

ObjectivesMitofusin 2 and ganglioside-induced differentiation-associated protein 1 are two main mitochondrial dynamics-related proteins. Dysfunction of these two proteins leads to different subtypes of Charcot–Marie–Tooth disease type 2A (CMT2A) and CMT2K. This study aims to report the pathological difference between CMT2A and CMT2K in a large cohort.MethodsThirty patients with molecularly confirmed CMT2A and nine with CMT2K were identified by next-generation sequencing. Sural nerve biopsies were performed in 29 patients.ResultsThe patients with both diseases showed length-dependent neuropathy with distal weakness, sensory loss, and no deep tendon reflex. Optic neuropathy appeared in 3/30 (10%) patients with CMT2A. Tendon contracture appeared in 4/9 (50.0%) patients with CMT2K. Sural biopsy revealed the loss of both myelinated and unmyelinated nerve fibers. Closely packed, irregularly oriented neurofilaments were observed in axons of unmyelinated nerve fibers in both diseases. Another important finding was the ubiquitous presence of smaller, rounded, and fragmented mitochondria in CMT2A and elongated mitochondria in CMT2K in the myelinated and unmyelinated axons.ConclusionThis study confirmed large diversity in phenotypes between CMT2A and CMT2K. Mitochondrial dynamics-related variations can induce different mitochondrial morphological changes and neurofilament accumulation in axons.

Expanding the Spectrum of Chronic Immune Sensory Polyradiculopathy

ObjectiveSensory loss with normal nerve conduction studies (NCS) from focal sensory root inflammatory demyelination is characteristic of chronic immune sensory polyradiculopathy (CISP). However, nonpure cases involving motor and distal sensory nerves exist (CISP-plus). We hypothesize that CISP-plus and CISP are fundamentally part of the same syndrome through comparison of clinical, neurophysiologic, and pathologic features.MethodsCISP-plus (primary dorsal root with lesser motor and sensory nerve involvement) and CISP cases were retrospectively analyzed (1986–2019).ResultsWe identified 44 CISP-plus and 28 CISP cases (n = 72) with 86% (38/44) of patients with CISP-plus and 79% (22/28) of patients with CISP experiencing imbalance. On examination, large fiber sensory loss was present in 98% (43/44) of patients with CISP-plus and 96% (27/28) of patients with CISP. Gait ataxia was evident in 93% (41/44) of patients with CISP-plus and 79% (22/28) of patients with CISP. Mild distal weakness was common in CISP-plus (75%, 33/44). NCS showed mild abnormalities in all patients with CISP-plus and were normal (by definition) in all patients with CISP. Elevated CSF protein, slowing of somatosensory evoked potentials, and MRI root enhancement occurred in most CISP-plus and CISP cases. Eleven CISP-plus nerve biopsies showed loss of large myelinated fibers and onion-bulb formations, most prominent in rootlet biopsies. Immunotherapy resulted in marked improvement of gait ataxia in 84% (27/32) of patients with CISP-plus and 93% (13/14) of patients with CISP with return to normal neurologic examination in half (25/46).ConclusionThe recognition of CISP-plus expands the spectrum of CIDP by combining CISP-plus (predominant sensory polyradiculopathy with mild motor and sensory nerve involvement) with pure CISP (focal sensory polyradiculopathy) together as proximal sensory CIDP.

Neuroprotective Effect of Chrysin in Rat Model of Parkinsons Disease: Histopathological Evidence

Parkinson’s disease (PD) is a neurodegenerative ailment that worsens over time. PD is characterized by severe motor and non-motor symptoms. Because there is no cure for Parkinson's disease, current treatments heavily rely on relieving symptoms. The current research explores the histopathological changes in the different brain regions including the cerebral cortex, hippocampus, and striatum after subcutaneous rotenone administration every other day for 21 days in adult male Wistar rats. Substantial morphological changes were noticed in cell area. Sections examined showed severe neuronal loss and excessive appearance of abnormal damaged, shrunken red neurons, intercellular edema and vacuolation of intercellular neuropile and loss of myelinated fibers. After the last rotenone injection, chrysin and L-dopa were given for 28 days. The findings showed that chrysin treatment displayed significant improvement in the neuronal architecture and decrease of damage caused by rotenone in different brain regions. This appeared in the form of moderate protective efficacy with the persistence of loss in normal neuronal densities. However, combined treatment of rotenone-injected animals with chrysin and L-dopa was associated with more records of visible intact neurons and fewer records of abnormal degenerative changes in various brain neuronal areas This study concludes that chrysin may be a useful drug alone or with L-dopa for the treatment of rotenone-induced PD.

Two independent mouse lines carrying the Nav1.7 I228M gain-of-function variant display dorsal root ganglion neuron hyperexcitability but a minimal pain phenotype.

Small-fiber neuropathy (SFN), characterized by distal unmyelinated or thinly myelinated fiber loss, produces a combination of sensory dysfunction and neuropathic pain. Gain-of-function variants in the sodium channel Nav1.7 that produce dorsal root ganglion (DRG) neuron hyperexcitability are present in 5% to 10% of patients with idiopathic painful SFN. We created 2 independent knock-in mouse lines carrying the Nav1.7 I228M gain-of-function variant, found in idiopathic SFN. Whole-cell patch-clamp and multielectrode array recordings show that Nav1.7 I228M knock-in DRG neurons are hyperexcitable compared with wild-type littermate-control neurons, but despite this, Nav1.7 I228M mice do not display mechanical or thermal hyperalgesia or intraepidermal nerve fiber loss in vivo. Therefore, although these 2 Nav1.7 I228M knock-in mouse lines recapitulate the DRG neuron hyperexcitability associated with gain-of-function mutations in Nav1.7, they do not recapitulate the pain or neuropathy phenotypes seen in patients. We suggest that the relationship between hyperexcitability in sensory neurons and the pain experienced by these patients may be more complex than previously appreciated and highlights the challenges in modelling channelopathy pain disorders in mice.

Impaired NDRG1 functions in Schwann cells cause demyelinating neuropathy in a dog model of Charcot-Marie-Tooth type 4D

Mutations in the N-myc downstream-regulated gene 1 (NDRG1) cause degenerative polyneuropathy in ways that are poorly understood. We have investigated Alaskan Malamute dogs with neuropathy caused by a missense mutation in NDRG1. In affected animals, nerve levels of NDRG1 protein were reduced by more than 70% (p< 0.03). Nerve fibers were thinly myelinated, loss of large myelinated fibers was pronounced and teased fiber preparations showed both demyelination and remyelination. Inclusions of filamentous material containing actin were present in adaxonal Schwann cell cytoplasm and Schmidt-Lanterman clefts. This condition strongly resembles the human Charcot-Marie-Tooth type 4D. However, the focally folded myelin with adaxonal infoldings segregating the axon found in this study are ultrastructural changes not described in the human disease. Furthermore, lipidomic analysis revealed a profound loss of peripheral nerve lipids. Our data suggest that the low levels of mutant NDRG1 is insufficient to support Schwann cells in maintaining myelin homeostasis.

EP30 Sensory ganglionopathy as a possible presenting feature of Sjögren’s syndrome

Case report - IntroductionPrimary Sjögren’s syndrome is a systemic autoimmune disease affecting the exocrine glands, commonly resulting in dryness of mouth and eyes. It can also rarely present with neurological symptoms most commonly peripheral neuropathies. The case highlights a rare case of sensory and motor neuropathy with some features suggestive of Sjögren’s syndrome as an underlying diagnosis.Case report - Case descriptionA 54-year-old Caucasian lady was transferred from a local hospital for specialist neurology care. She described widespread paraesthesia over two months progressing to lower limb weakness worsening over a two-day period. Her symptoms further progressed to involve her arms and new blurred vision. On further questioning she reported previous severe mouth ulcers, possible genital ulcers and painful jaw swelling with long standing history of dry mouth. On thorough neurological examination, the positive findings were mild ptosis of the right eye, paraesthesia on palpation of face, upper limbs had a flaccid tone with reduced power and pseudoathetosis of outstretched arms, reduced proprioception, and absent reflexes. Lower limbs were more affected with worse power and absent proprioception. Schirmer’s test showed normal tear production but saliva production was reduced.MRI brain and spine were reported as pathological enhancement in both optic nerves, no obvious brain parenchymal abnormality, no obvious spinal cord abnormality. Lumbar puncture CSF pro 0.38, white cells 12 (poly 50%, mono 50%), red cells 3700, no organisms on gram stain, opening pressure 21.5 cmH2O. Sural nerve biopsy demonstrated profound loss of sensory axons, severe loss of large myelinated fibres in all fascicles with motor nerve involvement. Muscle biopsy demonstrated chronic neurogenic atrophy. Rheumatology screen showed positive anti Ro 52 antibodies (on an extended myositis screen). EMG demonstrated neurophysiological evidence of widespread marked loss of sensory axons in the upper and lower limbs and partial loss of motor axons in several lower limb territories. USS parotid glands showed some possibly mildly abnormal areas, minor salivary gland biopsy was normal. She received methylprednisolone, IV immunoglobulin and two courses of plasma exchange. Given some improvement following this treatment, further immunosuppression was felt to be appropriate. Initially Mycofenolate mofetil was started and Rituximab is now being considered.Case report - DiscussionThis case demonstrates a mixed neuropathy picture. Following thorough investigations, many differential diagnoses of mixed neuropathy were considered and excluded (e.g. Guillain Barre, Syphilis, MS, HIV, Hepatitis). Neurological symptoms can develop before the onset of sicca symptoms in Sjögren’s syndrome. With a positive Anti Ro52, xerostomia and clinical improvement with methylprednisolone and plasmaphereses it seems likely there is an underlying autoimmune diagnosis in this case and despite a normal biopsy she would meet the 2016 ACR/EULAR classification criteria for Sjögren’s syndrome.Case report - Key learning pointsSjögren’s syndrome should be considered as a potential underlying cause in patients with a sensory ganglionopathy.Neurological symptoms can develop before the onset of sicca symptoms in Sjögren’s syndrome.